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NG9-1-1: Why we need data to be complete

As we stated in the first blog post in this series (NG9-1-1 puts GIS on its map), next-generation 9-1-1 replaces the existing analog 9-1-1 telephone system with a digital Internet Protocol (IP)-based architecture. NG9-1-1 will allow public safety professionals to receive 9-1-1 ‘calls’ from any digital device capable of accessing the Internet. In the second post (NG9-1-1: A game changer in public safety), we talked about GIS evolving into a critical component of NG9-1-1. In this blog post, Holly Barkwell, Canadian Region Director of the National Emergency Number Association (NENA) explains why NG9-1-1 needs a complete GIS dataset to function properly.

To route calls to the appropriate PSAP1, the current 9-1-1 system uses an MSAG2 or SAG database for landline calls and the cellular tower address for mobile devices. When the call is received, the PSAP operator sees the caller’s location (based on civic address for landline, and calculated based on triangulation or cell tower location for wireless) displayed on their mapping system. Once the PSAP call taker has confirmed the location and type of emergency, dispatchers use the confirmed incident location to manage the response.

I am sure you’ll agree that calculated location of wireless calls is a significant problem for 9-1-1. The wireless device location is calculated (not exact), so operators must spend additional time confirming the location of the incident (see image above). However, once the transition to NG9-1-1 is complete, a much richer set of data, including device-based location coordinates will be available to the PSAP, resulting in much greater wireless location accuracy. But, if the GIS data that supports NG9-1-1 is incomplete in any way, calls could still be routed to the wrong PSAP and/or a delay in confirmation of the location of the emergency may occur, which in turn delays response.

The new location-based process will expedite the emergency response system to a great extent, but it will also require up-to-date and complete GIS data.

While public safety agencies have used spatial data for years, the dependence on this data will gain a new significance with NG9-1-1. So much so that the effectiveness of the public safety system will depend directly on the quality of GIS data. In anticipation of this need, the Emergency Services Working Group (ESWG) is developing specifications and best management practices for the GIS data used in NG9-1-1. Three broad categories for this data have been developed: required, strongly recommended and recommended. The interim GIS content and standards specification recommendations will be submitted by the ESWG to the CRTC3 later this summer. When the Commission issues its response to the interim report, we will publish more information about the GIS data model and standards for Canada.

Data Completeness

Currently, data errors (missing address ranges, missing roads and other data) are identified and resolved during the MSAG/SAG build and maintenance processes. In NG9-1-1 however, the MSAG/SAG will eventually be replaced with geo-based call routing functionality which will read GIS data directly. As a result, GIS data completeness must be a priority. You may question, what does one mean by data completeness? Here are some examples of what it implies to have complete data:

  1. No coverage gaps
    • in the centreline road network.
      • (In rural or hinterland areas, resource roads used for activities such as forestry and mining are also needed.)
    • between emergency service areas (PSAPs, Police, Fire or EMS boundaries). 
      • The local government or emergency service usually provide PSAP boundaries and emergency services zone boundaries. Gaps must be resolved when PSAP areas from one local government abut its neighbours (know thy neighbour!).
  2. no missing or incorrect address ranges
  3. meet the minimum (required) content level defined by ESWG

As with 9-1-1 today, street centrelines with associated attributes and address ranges will continue to be the mainstay in NG9-1-1. In some cases, local governments may not be providing all ‘roads’ to 9-1-1 (for example, construction roads, private lanes, business parks and campuses). If there is a passageway for vehicles or pathway for foot access, 9-1-1 and responding emergency services will need to know about it.

The following imagery and map (open data sources) show changes that are not in the local government’s existing road network dataset. Can you imagine how this might impact the efficiency of a public safety agency’s response in an emergency?

Ancillary data for the NG9-1-1 system

PSAP call takers/dispatchers see call locations represented as a point on a map. Therefore, dispatchers and responders need and depend on ancillary GIS data to better understand the location and nature of the 9-1-1 call. Ancillary information helps confirm and refine the location of the emergency and provides better context to the dispatcher. Ancillary information can include address points, aerial/satellite imagery, building outlines, hydrology, landforms and property parcels. 

Keep in mind that in many cases, ancillary data is currently not included in the 9-1-1 core dataset.  Therefore, new procedures are required to get this information from the authorized data provider to PSAPs and responders.

To summarize, complete and standards-based data strengthens the emergency response system, which in turn, helps save lives and protects property. GIS data and processes will play increasingly important roles in NG9-1-1. Missing, incomplete or inaccurate data will delay locating callers and timely response to emergencies. As such, GIS professionals at every level will need to ensure their data meets or exceeds the national standards. Our future blogs will explain these standards as they develop, discuss ways to address data issues and illustrate–using case studies–how other agencies meet new requirements.

Stay tuned.


PSAP1 – Public Safety Answering Point (a 9-1-1 emergency call centre). There are currently 292 PSAPs in Canada.

MSAG2 – Master Street Address Guide is a cross-reference database of phone number and address with the PSAP service area.

CRTC3 – Canadian Radio-Television & Telecommunications Commission – the Canadian regulator for telecommunications service providers nationally. The ESWG provides recommendations to the CRTC to help ensure the successful implementation of NG9-1-1 in Canada (

About the Author

David Hamilton is the Public Safety Industry Manager for Esri Canada. His efforts are focused on advising customers how to use GIS technology to improve all areas of public safety, specifically (NG)9-1-1, law enforcement, fire services, emergency medical services, emergency management, and search and rescue. Prior to joining Esri Canada in 2010, David managed the GIS for E-Comm 9-1-1 in Vancouver, and worked for the RCMP at the Integrated Security Unit for the 2010 Olympic Winter Games where he managed their Common Operating Picture. Being active has been a major part of David’s personal life; soccer, track & field, skiing, cycling, hiking and now kayaking are all among his favourite activities.

Profile Photo of David Hamilton